Bottom screen for fluidized bed apparatus

Abstract

A fluidized bed apparatus comprises a container 18 and a bottom screen 16. The screen 16 comprises a perforated plate 28 having a plurality of large openings therein above each of which is secured a perforated cone 34. Fluid blown through a duct 12 passes through the perforations in the plate 28 and the perforations in the cones 34 into material 10 which is thereby fluidized. Circulation of the material 10 is rendered more uniform and the risk of damage lessened.

I claim: 
     
       1. A fluidized bed apparatus comprising a substantially planar bottom plate having apertures and provided with a plurality of openings therethrough,   and a plurality of perforated cones secured side by side with each said cone above one of said openings in said bottom plate, the height of said cones being from two to three times their base diameter.   
     
     
       2. The apparatus of claim 1 wherein the cones have an apex cone angle of 25° to 28°. 
     
     
       3. The apparatus of claim 1 which comprises at least five said cones and the ratio of the base diameter of each cone to the diameter of the bottom plate is from 1:5 to 1:8. 
     
     
       4. The apparatus of claim 3 wherein one said cone is arranged centrally on said bottom plate and the remaining said cones are arranged around said central cone. 
     
     
       5. A fluidized bed apparatus comprising a container having a cylindrical or frusto-conical wall of circular contour,   a substantially planar apertured bottom plate arranged within said wall and provided with a plurality of spaced openings in said bottom plate,   a plurality of perforated cones secured side by side with each said cone above one of said openings in said bottom plate,   deflector elements of gibbous rectangular outline arranged in the angle between said bottom plate and said container wall, each element being of symmetrical shape in relation to the perpendicular plane of symmetry between two adjacent said cones and having an edge disposed along this plane of symmetry.   
     
     
       6. The apparatus of claims 1, 2, 3, or 5 wherein an adjustable throttle member is associated with each of said openings in said bottom plate. 
     
     
       7. A fluidized bed apparatus comprising a substantially planar bottom plate having apertures and provided with a plurality of openings therethrough,   a plurality of perforated cones secured side by side with each said cone above one of said openings in said bottom plate,   an adjustable throttle member associated with each of said openings in said bottom plate,   each of said throttle members adapted to move up and down within a bell arranged below said bottom plate,   and a spring downwardly biasing each of said throttle members.   
     
     
       8. The apparatus of claim 1, 5, or 7 wherein spray nozzles connected to a fluid-carrying pipe are arranged on said cones. 
     
     
       9. The apparatus of claim 8 wherein said spray nozzles are arranged at the apices of said cones and are designed to spray a fluid in an angular zone of at least 90° that is symmetrical in relation to the axis of said cone concerned.